A heavy duty truck wheel hub rotates on bearings as part of a wheel hub assembly. A non-rotating spindle supports the wheel hub and bearing arrangement. A hub cap assembly covers and seals an open end of the wheel hub assembly. The function of the hubcap assembly is to contain a lubricant within the wheel hub assembly, to prevent contaminants from entering the wheel hub assembly, and to allow for ready checking of the lubricant, which is typically an oil or a low viscosity grease, and to allow addition of the lubricant. The hubcap assembly is typically bolted onto the wheel hub assembly. Further, the hub cap assembly includes a centrally located opening to receive a plug assembly.
It is an object of the present invention to provide an improved hub cap assembly with an improved plug assembly to lessen the potential of lubricant leaks out of the hub cap and to allow for proper dispersion of the lubricant within the hubcap and wheel hub assembly.